The only methadone program in Lowell, Habit OPCO, is trying to finalize a move to a new location near the Chelmsford line despite strong opposition from representatives of that neighboring town, who cite the fact that there are houses of worship, homes, and a preschool in close proximity. The clinic’s lease on its current location at Wannalancit Mills expired Sept. 30, though it remains open. Habit OPCO has filed two separate lawsuits against the city challenging zoning guidelines and alleging discrimination under the Americans with Disabilities Act. Lowell Department of Public Health officials are eager to resolve the issue, as the clinic is the city’s only program for the treatment of opiate addiction and serves an estimated 800 patients.